Gas-containing enclosures may be advantageous in a variety of applications. Generally, an enclosure is formed by connecting two or more sections using, e.g., mechanical fasteners, welds, or adhesives. One or more components are placed within the enclosure, and the enclosure is filled with a gas or gases, e.g., an inert gas. The completed enclosure contains the gas environment and one or more components protected by the enclosure.
For example, some hard disk drives are protected within an enclosure. The enclosure itself is generally located in an air environment, while the interior of the enclosure is filled with an inert gas (e.g., helium). Generally, the helium environment within the hard disk drive enclosure reduces both the energy required to spin the platters and the sensitivity of the head to ambient pressure fly height. The helium environment also may allow manufacturers to build drives with a lower fly height, leading to faster data access and retrieval rates.
The joints where the sections of an enclosure are connected are susceptible to leaks allowing gases within the enclosure to leave and/or ambient gases to enter the enclosure. In some applications, the enclosure may be sealed using, e.g., adhesives, gaskets and/or seals to minimize or substantially eliminate the flow of gases between the ambient environment and the interior of the enclosure. However, gases may diffuse through the materials used to seal the enclosure (e.g., the adhesives and gaskets). Whether by leaking, diffusion, or some other mechanism, the relative amount of desired gas within the enclosure generally diminishes over time.
Generally, to be effective, the desired gas environment within the enclosure should be maintained for the life of the components, which may be years (e.g., two, three, or five years, or even longer). Therefore, it is often desirable to replenish the gas within the enclosure to extend its useful life. One method of replenishment requires breaking a connection between sections of the enclosure, refilling the enclosure with gas, and resealing it. Another method includes equipping the enclosure with a fill-port and using an external gas supply to replenish the environment within the enclosure. Both methods may require removing the enclosure from its use environment for filling, or providing additional space around the enclosure to provide access. The presence of the fill port also presents a greater opportunity for leaks and may require additional gaskets or seals with their potential to permit diffusion of the desired gas out from the enclosure, and/or diffusion of ambient gases into the enclosure.
Another replenishment source comprises an impermeable storage tank for holding the gas, one or more valves to permit gas to exit the tank, and a series of controls to operate the valve(s). While the use of such devices may not require opening the enclosure or the presence of a fill port, the size, weight, and complexity of such devices may be undesirable in many applications.